This invention relates to an apparatus for controlling the rotation of a rotating body in a recording and/or reproducing apparatus, and more particularly to an apparatus for controlling the rotation of a direct current motor used to drive rotating heads or a capstan in the recording/reproducing apparatus. The motor is so controlled that the rotational speed and the rotational phase of the rotating heads or a capstan become and remain constant.
The present invention is one relating to and improving the invention described in a copending U.S. Pat. application Ser. No. 379,855, "APPARATUS FOR CONTROLLING ROTATION OF ROTATING BODIES AT CONSTANT SPEED" filed on July 16, 1973, now abandoned.
Various proposals have heretofore been made for a so-called head servo system. These systems control the rotation of rotating heads for recording/reproducing video signals on/from a magnetic tape. Or, a so-called capstan servo system controls the rotation of a capstan for driving a magnetic tape and causing it to travel in a recording/reproducing apparatus. In all apparatus based on these previously proposed systems, however, the control circuits tend to become complex and large, and large amounts of electric power are consumed. It has been difficult to realize in practice a device which has a miniature and simple circuit organization and, moreover, is capable of controlling rotation with a high degree of accuracy.
On one hand, there has recently been a great effort to miniaturize apparatus for magnetic recording and/or reproducing of video signals. The recent trend has been toward a wide use of a apparatus of portable and very small type in which a magnetic tape is accommodated within a cartridge. The power source is self contained within the apparatus.
Accordingly, there is great demand for the practical realization of a rotation control system and apparatus suitable for video-signal recording and/or reproducing apparatus, particularly of the above mentioned portable type.